Adiponectin secretion is regulated by SIRT1 and the endoplasmic reticulum oxidoreductase ero1-lα

Adiponectin is secreted from adipose tissue in response to metabolic effectors in order to sensitize the liver and muscle to insulin. Reduced circulating levels of adiponectin that usually accompany obesity contribute to the associated insulin resistance. The molecular mechanisms controlling the production of adiponectin are essentially unknown. In this report, we demonstrate that the endoplasmic reticulum (ER) oxidoreductase Erol-L alpha and effectors modulating peroxisome proliferator-activated receptor y (PPARy) and SIRT1 activities regulate secretion of adiponectin from 3T3-L1 adipocytes. Specifically, adiponectin secretion and Erol-L alpha expression are induced during the early phase of adipogenesis but are then down-regulated during the terminal phase, coincident with an increased expression of SIRT1. Suppression of SIRT1 or activation of PPARy enhances Erol-L alpha expression and stimulates secretion of high-molecular-weight complexes of adiponectin in mature adipocytes. Suppression of Erol-L alpha through expression of a corresponding small interfering RNA reduces adiponectin secretion during the differentiation of 3T3-L1 preadipocytes. Moreover, ectopic expression of Erol-L alpha in Erol-L alpha-deficient 3T3 fibroblasts stimulates the secretion of adiponectin following their conversion into adipocytes and prevents the suppression of adiponectin secretion in response to activation of SIRT1 by exposure to resveratrol. These findings provide a framework to understand the mechanisms by which adipocytes regulate secretion of adiponectin in response to various metabolic states.